1. Field of the Invention
The present invention pertains to endoscope couplers for optically and mechanically coupling an endoscope to a video camera. More particularly, the invention relates to endoscope couplers which enable relative rotation of the endoscope and camera about the endoscope axis.
2. Description of the Prior Art
Endoscopes have become widely utilized in surgery for viewing body cavities and organs to permit performance of diagnostic and surgical procedures internally without the need for invasive surgical procedures. An endoscope is typically inserted through a small incision or portal or natural body passage to provide access to the body cavity. A lens at a distal end of the endoscope is positioned to receive light reflected from a site to be observed, and images of the site can be viewed remotely to conduct diagnostic examinations and to perform closed, or endoscopic surgery. As used herein, the term endoscope refers generically to viewing devices for remotely observing otherwise inaccessible body cavities with minimal trauma and intrusion, including but not limited to arthroscopes, colonoscopes, bronchoscopes, hysteroscopes, cystoscopes, sigmoido-scopes, laparoscopes and ureterscopes, etc.
Endoscopes are sometimes supplied with an eyepiece at the proximal end thereof, and relay lenses in the endoscope typically produce an image for direct viewing through the eyepiece. However, adaptation of video camera technology to endoscopy imaging has enabled the output image of an endoscope to be viewed on a video monitor. Specifically, a video camera is electronically coupled to the video monitor and optically and mechanically coupled with the proximal end of the endoscope. Indirect or video monitor viewing of endoscopic images provides numerous benefits over direct viewing through an eyepiece, including: protection of a direct viewer's vision from high intensity illumination passed through the endoscope and reflecting off bodily tissue; enhancement of operator comfort and freedom of movement; increased endoscope utility and efficiency; reduction in the time required to conduct many endoscopic procedures; simultaneous viewing of endoscopic images by more than one person; and recordation and real time transmission of images of surgical procedures.
An endoscope coupler is required to couple the proximal end of the endoscope to the video camera and may be made as a separate device or in combination with either the endoscope or the video camera or both. Illustrative endoscope couplers are shown in U.S. Pat. No. 4,569,333 (Bel et al.); U.S. Pat. No. 4,611,888 (Prenovitz et al.); U.S. Pat. No. 4,740,058 (Hori et al.); U.S. Pat. No. 4,781,448 (Chatenever et al.); U.S. Pat. No. 4,807,594 (Chatenever); U.S. Pat. No. 4,844,071 (Chen et al.); U.S. Pat. No. 4,969,450 (Chinnock et al.); U.S. Pat. No. 5,056,902 (Chinnock et al.) and U.S. Pat. No. 5,359,992 (Hori et al.). Endoscope couplers sometimes include a cylindrical body which may be closed at opposing ends by end windows and contain a lens holder carrying one or more lenses longitudinally movable within the body to optically adjust an image from the endoscope onto a focal plane of the camera. The optical adjustments most commonly used may be a focus and/or zoom adjustment. Sometimes, endoscope couplers operate with the eyepiece of an endoscope and other times the eyepiece is replaced with an optical arrangement which must be viewed through the camera and monitor (that is, no eyepiece is available).
In addition to enabling optical adjustments, in certain applications such as the urology field, it is often necessary to maintain the camera in a fixed position while rotating the endoscope about its axis in order to view the surgical site. Therefore, rotatable endoscopic couplers have been developed to enable this rotation of the scope relative to the camera. Such couplers may not include any optical components although they serve to properly position the proximal end of the scope relative to the distal end of the camera so the image planes are properly spaced along their common axis. Known rotatable endoscopic couplers generally include a distal ring, which may be fixedly attached to the proximal end of the endoscope, a proximal ring, which may be fixedly attached to a camera, and a rotatable interface between the two rings. The rotatable interface often includes a plain bearing structure (not ball bearings) and a selectively actuatable lock (such as a lever with a pin or cam) to selectively prevent rotation.
Additionally, it is advantageous for the surgeon to use only one hand to manipulate the scope or the camera thereby leaving the other hand free to operate various instruments during surgical procedures. Therefore, rotatable couplers must be easy to operate.
Aforementioned U.S. Pat. No. 4,969,450 (Chinnock et al.) discloses a rotatable coupler for a video arthroscope which can be held and controlled with one hand. The rotatability is achieved by closely fitting cylindrical members including bores and counterbores which are rotatable about their common axes and sealed with several O-rings.
Another example of a rotatable coupler is shown in U.S. Pat. No. 4,611,888 (Prenovitz et al.). The Prenovitz coupler consists of two sections rotatable with respect to one another, the front section being non-rotatably mounted to the proximal end of an arthroscope and the rear section being non-rotatably mounted to the distal end of a video camera. The image produced by the scope is rotatable relative to the camera by simply rotating the front section relative to the rear section.
In order to maintain sterile surgical conditions, all imaging components, including endoscope couplers, whether rotatable or not, must be sterilized before and after each use. Steam autoclaving has long been the best accepted method of sterilization and is used for all instruments that can withstand the necessary high temperature and pressure. Instruments that will not survive the steam autoclave process, such as video cameras and prior art endoscopic couplers are treated by less effective or less efficient means such as immersion in sterilization liquid or gas sterilization. However, there is no known conventional rotatable endoscopic coupler which can withstand repeated steam or other sterilization and all known rotatable endoscopic couplers are adversely affected by such.
While known prior art couplers are available to enable the rotation of the endoscopic image relative to the camera, all known rotatable couplers utilize bearing surfaces, which are rotatable relative to each other, and locking mechanisms in the form of cams and pins to frictionally engage the rotatable elements to lock them together when the desired angular orientation is achieved. Over time, these known rotatable coupler designs become more and more difficult to operate because of the build up of residue caused by improper cleaning as well as the deterioration of the cooperating parts caused by their exposure to the harsh environments of autoclaves. This deterioration eventually leads to the inability to easily operate the rotatable coupler with one hand and eventually leads to the inability to rotate the coupler at all. These prior art couplers must then be totally rebuilt or replaced.
An improved rotatable coupler design is necessary in order to enable the autoclavability of rotatable endoscopic couplers and improve their performance over an extended period of time.
It is, therefore, an object of this invention to produce a rotatable endoscope coupler for joining an endoscope to a camera.
It is also an object of this invention to provide a rotatable endoscope coupler capable of being repeatedly subjected to an autoclave without significant deterioration of performance.
It is still another object of this invention to produce a rotatable endoscope coupler incorporating ball bearings which are adapted to withstand the autoclave environment.
It is still another object of this invention to produce a rotatable endoscope coupler capable of being easily disassembled for repair.
It is also an object of the present invention to provide an endoscope coupler that may be quickly and easily inserted between an endoscope and a video camera or may be formed as an integral part of either the endoscope or the video camera or both.